Electrical heating device for curling tongs



Oct. 25, 1932. A. REHM 1,884,232

ELECTRICAL HEATING DEVICE FOR CURLING TQNGS Filed Nov. 18. 1929 is iPatented Oct. 25, 1932 ALFBED Km, 01' STUTTGABT, GERMANY,

PATENT OFFICE ASSIGNOR 1'0 ROBERT BOSCH AKTIENGE- SELLSGEAFT, OFSTUITGART, GERMANY ELECTRICAL HEATING DEVICE FOR CURLING TONGSApplication filed ll'ovcmber 1a, 1929, Serial No.

The-present invention relates to electrically heated curlingtongs.

In curling tongs having a built-in heating resistance, the temperatureof the curling tongs is usually regulated by an adjustable seriesresistance, which is housed in a container secured to the wall. Thisseries resistance is disadvantageous as it consumes considerable power.Also the adjustment through the series resistance does not alwayscorrespond to the actual temperature of the the curling tongues when inuse, as this is also dependent on the momentary heat delive a of thecurling tongs.

According to the present invention a temperature controlled switch isinstalled in the heating tong element of a curling tongs which canautomatically switch the current for the heat resistance oif and on asthe temperature rises or falls.

One form of construction of the invention is illustrated by way ofexample in partial section in the accompanying drawing.

Inserted in .the hollow heating tong element-1 of a air of curling tongsis a tube 2 of zinc or ot er metal of relatively high coelficient ofexpansion into which an insulated tube 3 is introduced.

Mounted in the upper end of the tube 2 is a rod 4: of quartz glass orthe like material of relatively low coeflicient of expansion. A heatingresistance 5 is wound on the rod 4.

Mounted on the free end of the rod 4 is a boss 6 of iron or otherelectrical conducting material provided with outer threads on which isscrewed an iron sleeve 7. A pin 8 which has a flange-shaped stop 9 and acontact head 10 is disposed within the boss 6 and sleeve 7. The free endof the sleeve 7 is bent over to secure an annular disc 11. A helicalspring 7' is tensioned between the flange of the sleeve 6 and the stop 9of the pinl8 and tends to force the stop 9 against the annular disc 11.

A pin 14 is screwed into a tube-shaped eX- 408,065, and in GermanyIovember 24, 1928.

tension 13 of the tube 2 and carries an insulated contact or bridge 16through an intermediate insulator 15 the contact being of truncatedconical form. A contact spring 17 secured to the end of cylinder 2 butinsulated therefrom is adapted for 'contact with the bridge 16 and isconnected to a source of current by means of a lead 18.

The screw pin 14 has a head '20 provided with divisions 19 and'theposition of the divisions can be read ofl the end of an indicator 21,secured to the heated tong element 1.

During installation the position of the pin 8 relative to the contact 16can be adjusted by screwing the collar 7 onto the sleeve 6. One end ofthe heat resistance 5 is connected to the sleeve 6 and through this tothe pin 8; the other end of the heat resistance being attached to-a lead22. a

As the temperature of the heating resistance rises the zinc tube 2expands more than the quartz rod 4. The pin 8 follows the expansion ofthe zinc rod 2 until the stop 9 abuts against the annular disc 11. Ifthe temperature of the heated tong element rises still further,thenthecontacts 10 and 16 separate on the further expansion of the Zinc rod andthe heating resistance is thereby switched ofi.

During the subsequent cooling of the curling tongs the zinc rod 2 againcontracts so that the contacts 1) and 16 again touch.

By screwing out the screw pin 14., the position of the contact 16relative to the contact 10 is altered in such a way that the opening ofthe pair of contacts is efiected and a lower temperature than formerlyis provided. The position of the screw pin 8 canbe read off by means ofthe divisions 19 gauged according to the temperatures.

The form of construction shown by way of example has the advantage thatthe heat acting on the wall of the heated tong element influences theheat switch directly and the heat arising during the practical use ofthe curling tongs is thereby controlled.

In a modified form of construction the tube 2 may itself form a heatedtong element.

Again a difierently constructed heat switch can be installed in thecurling tongs, for example a switch working with a bimetallic spring.

I claim:

1. An electrical heater for'curling tongs comprising a hollow casing, aheating resistance within said casing, two longitudinal members ofdifferent heat coefficient of expansion connected together at one end, apair of switch contact elements in series with said resistance eachcontact element being connected to the free end of one of saidlongitudinal members and an adjustable bridging member between saidswitch contact elements.

2. An electrical heating device for curling tongs comprising a cylinderformed of ma: terial of relatively high temperature coefiicient ofexpansion, a rod within and connected at one end to said cylinder formedof material of relatively low temperature coefficient of expansion, aheating resistance wound upon said rod. a resiliently axiallydisplaceable contact element at the free end of said rod and in serieswith said resistance, means for limiting the displacement of saidcontact element in one direction relatively to the rod a resilientswitch contact element at the free end of the cylinder in series withthe resistance and an adjustable bridge intermediate of said switchcontact elements.

3. An electrical heating device for curling tongs comprising a cylinderformed of material of relatively high temperature coefiilowertemperature coeflicient of expansion than said casing and being mountedat one end within said casing and having its free end facing saidinsulated contact, a resilient contact element mounted on the free endof said rod, an adjustable bridge connecting said contact elements, anda heatin winding wound upon said rod and having its circuit completedthrough said contacts and bridge.

In testimony whereof I have hereunto afiixed my signature.

ALFRED REHM.

cient of expansion, a rod within and connected at one end to saidcylinder formed of material of relatively low temperature coefiicient ofexpansion, a heating resistance wound upon said rod, a resilientlyaxially displaceable contact element at the free end of said rod and inseries with said resistance.

means for limiting the displacement of said contact element in onedirection relatively to the rod, and a switch contact element at thefree end of the cylinder in series with the resistance.

4. An electrical heating device for curling tongs and the likecomprising a hollow cylindrical casing, an insulated contact mounted inone end of said casing, a rod having a lower temperature coeflicient ofexpansion than said casing and being mounted at one end within saidcasing and having its free end facing said insulated contact, aresilient contact element mounted on the free end of said rod andcooperating with said insulated contact, and a heating winding woundupon said rod within said casing and having its circuit completedthrough said contacts.

5. An electrical heating device for curling tongs and the likecomprising a hollow cy-v lindrical casing, an insulated contact mountedin one end of said casing, a rod having a

